The present invention relates to a monoclonal antibody against human mononuclear leukocytes with the ability to inhibit transendothelial migration of the leukocytes in cocultures with vascular endothelial cell monolayers, said monoclonal antibody being useful for the study and treatment of inflammatory response; to a hybridoma producing this antibody.
Inflammatory reaction, one of the most important responses in the body defense, not only diminishes tissue damage caused by bacterial or viral infections but also promotes repair of such injured tissue. However, the inflammation often induces progressive disorders, such as autoimmune diseases or other incurable diseases of unknown cause. For the treatment of autoimmune diseases, therefore, it is essential to elucidate the mechanisms and pathological profiles of such inflammatory response. Extravasation of peripheral blood leukocytes which is observed in the earliest stage of inflammation is an important target in the therapeutic strategy for chronic inflammatory diseases.
By the use of monoclonal antibodies or molecular biological techniques, the mechanisms of leukocyte extravasation have been extensively investigated with great progress in the 1990s. At present, it is generally accepted that the process of leukocyte extravasation consists of three serial steps. Briefly, the initial step is leukocyte attachment to and rolling along the luminal surface of endothelium that is mediated by selectin. Subsequently, the leukocyte integrins are activated during this contact with the endothelial surface, by which tight adhesion of leukocytes to the endothelial cell surface occurs. The final step is the process of transendothelial migration after their tight adhesion. Although it has been hypothesized that CD31 promotes transmigration of NK cells, neutrophils, and monocytes, little is known about the molecular mechanism of transmigration of T cells which play a central role in immune reaction. Subsequent transmigration of T cells that adhered to endothelial cells is selective, but not random, as indicated by their phenotypic characteristics. Molecules that mediate the selective migration are thought to play significant roles in the onset and progression of chronic inflammatory diseases. Thus, it is important for researchers to study the nature and function of the molecules involved in the mechanisms of inflammation and the therapeutic means. For that reason monoclonal antibodies against the molecules are needed; however, thus far, there have been no such antibodies.
Accordingly, the purpose of the present invention is to provide a monoclonal antibody directed to a molecule that participates in the transmigration process (diapedesis) of human mononuclear leukocytes after their adhesion to vascular endothelial cells.
As a result of an extensive study for the purpose described above, the present inventor has developed a monoclonal antibody capable of inhibiting transmigration of human mononuclear leukocytes after their adhesion to vascular endothelial cells using the following methods: 1) a method of immunization with human mononuclear cells bound to human endothelial cells and migrated through human endothelial cell monolayers cultured on collagen gels into the gels below; 2) a method of screening for antibodies that inhibit transmigration of human mononuclear cells across endothelial cell monolayers cultured on collagen gels, but not their endothelial adhesion.
Thus, the present invention provides a monoclonal antibody against human mononuclear leukocytes which is capable of inhibiting transmigration of human mononuclear leukocytes after their adhesion to vascular endothelial cells.
In addition, the present invention provides a hybridoma producing the monoclonal antibody.